Nail biting and thumb sucking might actually be good for a child's health.
A new study, published in Pediatrics, reveals that children who bite their nails and suck their thumbs are about one-third less likely to develop certain allergies.
“Cat, grass, house dust mite, and dog [allergies] – those were reduced, some significantly, some borderline,” said study author Malcolm Sears, a researcher for the Firestone Institute for Respiratory Health at McMaster University School of Medicine, in Ontario, Canada.
“When they suck their thumbs or bite their nails they’re exposing themselves to additional microbes or dirt which is stimulating the immune system.”
Of course, the American Dental Association advises that while thumb- or finger-sucking is a natural reflex in young children, intense sucking can cause problems with a child’s tooth alignment.